<i>Leptosphaeria</i>
            rhodopsin: Bacteriorhodopsin-like proton pump from a eukaryote

Waschuk, Stephen A.; Bezerra, Arandi Ginane; Shi, Lichi; Brown, Leonid S.

doi:10.1073/pnas.0409659102

Cited by 219 publications

(199 citation statements)

References 27 publications

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“…In addition, opsin-encoding sequences have been identified in the genomes of the fungi Neurospora crassa (8), Fusarium fujikuroi (26), and Leptosphaeria maculans (17), but more examples are appearing as new fungal genomes become available. Recently, it has been demonstrated that the Leptosphaeria opsin acts as a bacteriorhodopsin-like proton pump (43). It was also shown that the Neurospora opsin NOP-1, when heterologously expressed in the yeast Pichia pastoris, forms an active photoreceptor exhibiting similar characteristics to the archaeal sensory rhodopsin II (7,9).…”

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confidence: 88%

Retinal Biosynthesis in Fungi: Characterization of the Carotenoid Oxygenase CarX fromFusarium fujikuroi

et al. 2007

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The car gene cluster of the ascomycete Fusarium fujikuroi encodes two enzymes responsible for torulene biosynthesis (CarRA and CarB), an opsin-like protein (CarO), and a putative carotenoid cleaving enzyme (CarX). It was presumed that CarX catalyzes the formation of the major carotenoid in F. fujikuroi, neurosporaxanthin, a cleavage product of torulene. However, targeted deletion of carX did not impede neurosporaxanthin biosynthesis. On the contrary, ⌬carX mutants showed a significant increase in the total carotenoid content, indicating an involvement of CarX in the regulation of the pathway. In this work, we investigated the enzymatic activity of CarX. The expression of the enzyme in ␤-carotene-accumulating Escherichia coli cells led to the formation of the opsin chromophore retinal. The identity of the product was proven by high-performance liquid chromatography and gas chromatography-mass spectrometry. Subsequent in vitro assays with heterologously expressed and purified CarX confirmed its ␤-carotene-cleaving activity and revealed its capability to produce retinal also from other substrates, such as ␥-carotene, torulene, and ␤-apo-8-carotenal. Our data indicate that the occurrence of at least one ␤-ionone ring in the substrate is required for the cleavage reaction and that the cleavage site is determined by the distance to the ␤-ionone ring. CarX represents the first retinal-synthesizing enzyme reported in the fungal kingdom so far. It seems likely that the formed retinal is involved in the regulation of the carotenoid biosynthetic pathway via a negative feedback mechanism.Carotenoids are widespread lipophilic pigments synthesized by all photosynthetic organisms and some nonphotosynthetic fungi and bacteria. These yellow, orange, and red isoprenoid compounds fulfill diverse functions in all taxa. In addition, carotenoids are the precursors of several physiologically essential compounds, like the ubiquitous chromophore retinal, the phytohormone abscisic acid (ABA), and the fungal sex hormone trisporic acid.The synthesis of these carotenoid cleavage products, known as apocarotenoids, is catalyzed in general by carotenoid oxygenases, which constitute a new nonheme iron enzyme family common in all taxa (for reviews, see references 1, 11, 15, and 24). Recently, the crystal structure of a member of this family, the Synechocystis apocarotenoid oxygenase, was elucidated at 2.4-Å resolution. The enzyme contains an Fe 2ϩ -4-His arrangement at the axis of a seven-bladed ␤-propeller chain fold covered by a dome formed by six large loops (20). It has also been shown that the 15,15Ј BCO I (␤-carotene oxygenase I) acts as a monooxygenase (21). However, recent investigations of AtCCD1 (Arabidopsis thaliana carotenoid cleavage dioxygenase 1) suggested a dioxygenase mechanism (31).VP14 (Viviparous 14), a maize enzyme mediating the oxidative cleavage of 9-cis-violaxanthin and 9Ј-cis-neoxanthin to form the precursor of ABA, xanthoxin, was the first molecularly identified carotenoid oxygenase (34). Data from sequenced genomes hav...

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confidence: 88%

Retinal Biosynthesis in Fungi: Characterization of the Carotenoid Oxygenase CarX fromFusarium fujikuroi

et al. 2007

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“…fivefold) in WKI. Bacteriorhodopsins are lightdependent proton pumps in archaea and eubacteria, and related proteins occur in some eukaryotes (Waschuk et al, 2005;Wada et al, 2011). Their presence in marine eukaryotic phytoplankton genomes is thought to result from lateral gene transfer from bacteria (Slamovits et al, 2011).…”

Section: Variation In Diatom Metabolic Pathways Across Communitiesmentioning

confidence: 99%

Metatranscriptomes reveal functional variation in diatom communities from the Antarctic Peninsula

et al. 2015

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Functional genomics of diatom-dominated communities from the Antarctic Peninsula was studied using comparative metatranscriptomics. Samples obtained from diatom-rich communities in the Bransfield Strait, the western Weddell Sea and sea ice in the Bellingshausen Sea/Wilkins Ice Shelf yielded more than 500K pyrosequencing reads that were combined to produce a global metatranscriptome assembly. Multi-gene phylogenies recovered three distinct communities, and diatom-assigned contigs further indicated little read-sharing between communities, validating an assembly-based annotation and analysis approach. Although functional analysis recovered a core of abundant shared annotations that were expressed across the three diatom communities, over 40% of annotations (but accounting for o10% of sequences) were community-specific. The two pelagic communities differed in their expression of N-metabolism and acquisition genes, which was almost absent in post-bloom conditions in the Weddell Sea community, while enrichment of transporters for ammonia and urea in Bransfield Strait diatoms suggests a physiological stance towards acquisition of reduced N-sources. The depletion of carbohydrate and energy metabolism pathways in sea ice relative to pelagic communities, together with increased light energy dissipation (via LHCSR proteins), photorespiration, and NO 3 − uptake and utilization all pointed to irradiance stress and/or inorganic carbon limitation within sea ice. Ice-binding proteins and cold-shock transcription factors were also enriched in sea ice diatoms. Surprisingly, the abundance of gene transcripts for the translational machinery tracked decreasing environmental temperature across only a 4°C range, possibly reflecting constraints on translational efficiency and protein production in cold environments.

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“…A striking characteristic of these rhodopsins is their wide range of seemingly dissimilar functions. Some are light-driven transporters, such as the proton pumps bacteriorhodopsin (BR) 2 in haloarchaea, xanthorhodopsin in halophilic bacteria, proteorhodopsin in marine bacteria, Leptosphaeria rhodopsin in fungi, and halorhodopsin (HR) in haloarchaea and in bacteria (3,(13)(14)(15)(16)(17). These proteins generate an electrochemical membrane potential upon light activation, which is utilized by ATP synthase to produce ATP (18).…”

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confidence: 99%

Spectral Tuning in Sensory Rhodopsin I from Salinibacter ruber

Sudo

Yuasa

Shibata

et al. 2011

Journal of Biological Chemistry

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Organisms utilize light as energy sources and as signals. Rhodopsins, which have seven transmembrane ␣-helices with retinal covalently linked to a conserved Lys residue, are found in various organisms as distant in evolution as bacteria, archaea, and eukarya. One of the most notable properties of rhodopsin molecules is the large variation in their absorption spectrum. Sensory rhodopsin I (SRI) and sensory rhodopsin II (SRII) function as photosensors and have similar properties (retinal composition, photocycle, structure, and function) except for their max (SRI, ϳ560 nm; SRII, ϳ500 nm). An expression system utilizing Escherichia coli and the high protein stability of a newly found SRI-like protein, SrSRI, enables studies of mutant proteins. To determine the residue contributing to the spectral shift from SRI to SRII, we constructed various SRI mutants, in which individual residues were substituted with the corresponding residues of SRII. Three such mutants of SrSRI showed a large spectral blue-shift (>14 nm) without a large alteration of their retinal composition. Two of them, A136Y and A200T, are newly discovered color tuning residues. In the triple mutant, the max was 525 nm. The inverse mutation of SRII (F134H/Y139A/ T204A) generated a spectral-shifted SRII toward longer wavelengths, although the effect is smaller than in the case of SRI, which is probably due to the lack of anion binding in the SRII mutant. Thus, half of the spectral shift from SRI to SRII could be explained by only those three residues taking into account the effect of Cl ؊ binding.

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Leptosphaeria rhodopsin: Bacteriorhodopsin-like proton pump from a eukaryote

Cited by 219 publications

References 27 publications

Retinal Biosynthesis in Fungi: Characterization of the Carotenoid Oxygenase CarX fromFusarium fujikuroi

Retinal Biosynthesis in Fungi: Characterization of the Carotenoid Oxygenase CarX fromFusarium fujikuroi

Metatranscriptomes reveal functional variation in diatom communities from the Antarctic Peninsula

Spectral Tuning in Sensory Rhodopsin I from Salinibacter ruber

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